Re-examination of a rare protosteloid amoeba Schizoplasmodiopsis micropunctata, and the revision of Tychosporium (Cavosteliida, Variosea, Amoebozoa)

The genus Schizoplasmodiopsis is one of the most morphologically diverse groups among the class Variosea. Recent phylogenetic studies suggest that Schizoplasmodiopsis is polyphyletic, but there are few taxonomic studies of this genus. We established S. micropunctata strain YIP-40, observed in detail its of morphology and lifecycle, and conducted a phylogenetic analysis. The phylogenetic analysis revealed that S. micropunctata was sister to Tychosporium acutostipes. Scanning electron microscopy showed S. micropunctata had a non-deciduous hilum structure that is unique to Tychosporium. The morphology of amoebae, mitotic behavior, and prespore cells of S. micropunctata also supported the close relationship to Tychosporium. We propose to transfer S. micropunctata to Tychosporium and emend the generic concept of Tychosporium to include this species.